A factorization theorem has been proven for DVCS in the Bjorken limit [1]}, [2]}. It allows one to compute the DVCS
amplitude as the product of some GPDs and a coefficient function that can be calculated perturbatively. GPDs are thus in very solid theoretical footing: at leading-twist level, all-order QCD-factorization theorems directly relate the GPDs to particular hard exclusive scattering processes. Therefore, GPDs are process-independent, universal quantities.
